Antenna



ANTENNA Filed July 1, 1930 INVENTOR NILS E. LINDENBLAD BY 7%@ /wv'c/ ATTORNEY Patented May 26, 1936 UNITED STATES ANTENNA Nils E. Lindenblad, Port Jefferson, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application July 1, 1930, Serial No. 465,088

15 Claims.

This invention relates to an antenna and has for one of its objects the provision of an end- -on antenna depending for its action upon standing wave phenomena.

If standing waves are produced upon successive radiators one-half wave length apart of opposite instantaneous polarity, radiation will occur in the line lof the radiators. To have such a system, I provide according tothe present invention, a plurality of linear radiators internally and externally connected by feeder members, the nal feeder members being short circuited in order to set up standing waves on the radiators. In this manner desired.endon radiation is obtained. -v f To prevent radiation from the feeder members is a further object of my present invention and I do so by paralleling the external feedermembers by adjacent looped conductors or-neutralizers upon which are standing waves of opposite instantaneous polarity to those on the feeder members. In this manner, due to the concentric opposite phase fields about the feeders and neutralizers, no radiation will ensue from the feeders.

Still a further object of my invention is to provide means for melting sleet or other frozen deposits upon the feeders, radiators and neutralizers; for, such deposits are detrimental to the desired standing wave phenomena.

My invention may best be understood by referring to the accompanying drawing in which I have shown diagrammatically a form of endon transmitting antenna embodying the principles outlined above.

Referring to the drawing a transmitter 2 supplies high frequency energy through blocking condensers 4, a radiationless transmission line 6 of known construction, to an antenna built according to my invention. To the transmission line B on the side of the blocking condensers 4 away from transmitter 2 is connected a source of heating energy 8 through radio frequency chokes I0. Io control the amount of heating current present in the antenna a switch I2 and a Variable resistance I4 is provided.

The antenna itself comprises two sections A, B each section being in square wave form, and as shown is arranged symmetrically about an axis I6. Y l

The pairs of linear radiators or oscillators I8, 20 are connected at their internal ends to feeder portions or members 22, and at their outer extremities to feeder members 24. Each of the feeders and radiators are, as indicated on .the

(Cl. Z-33) drawing, long.

The antenna is terminated by feeders 220, each, one-quarter wave length long and Vshort circuited by connection 222. In this manner the antenna is effectively closed circuited for heating currents.

As the internal feeders 22, that Vis to say, the feeders forming the hollows or troughs of the antenna are in close proximity, the fields thereabout are substantially concentric and consequently there is substantially no lradiation therefrom. H

This, however, is not true of the fields about feeders 24; and hence, if it were attempted to radiate or receive energy with the antenna so far described, a very poor directional characteristie would be found for the arrangement. The poor directional quality is due to the pick-up or radiation as the case may be, depending upon whether the antenna is used for receiving or transmitting, from external feeder members 24. One way of preventing radiant action of feeders 24 would be to provide concentric cylinders thereabout and possibly grounding these cylinders. However, they are open to objection due to their own natural periods and due to the long length of possible ground wires necessary in the cases of elevated antennae structures, and, therefore, they will more likely prove detrimental or useless rather than helpful. I prefer, therefore, to prevent radiant -action therefrom in the simpler manner shown.

As shown, the radiators are extended for a quarter Wave length and bent back upon themselves to form radiationless phase changers 30. Then, between the wave changers I connect neutralizers cr linear radiators 32 paralleling the external feeder members 24. In this manner, wires 32 are excited 180 degrees out of phase with their contiguous wires 24, and, because of this, radiation cancellation or neutralization is caused in a manner similar to that caused by the adjacent placing of internal feeders 22.

As shown the antenna system will produce sharp radiation in a direction along axis I6, the dotted lines 34 indicating the potential conditions existing in each radiator at a given instant due to the standing waves set up. As shown, it is clear that the potential waves in successive radiator pairs have phase displacements suitable for the production of end-on or in line radiation, radiation in a broadside `direction being canceled by the successive out of phase radiators.

substantially one-half Wave length As the desired standing wave phenomenon may be disturbed to a great extent by frozen 4deposits in the form of snow or sleet, according to my invention, I provide means to remove the same. By closing switch l2 heating energy either direct current or, if desired, low frequency currents such as are utilized in power work, passes serially through all of the radiating elements, feeders .and neutralizers of the antenna, removing therefrom the undesired 'frozen deposits. l

Dotted lines 36 indicate diagrammatica'lly catenary suspension elements for the antenna which may support it either vertically, horizontally or at any desired angle.

Although the foregoing description indicates the manner in which the antenna is utilized for end-on electromagnetic action, the invention is.

not limited thereto but may also be used in .similar fashion for broadside propagation or recepfilon of electromagnetic Waves, renin fotherwords, in a direction perpendicular to the plane of the radiators. To accomplish breadside action, `lthe internal and 'external feeders should be '.made :one wave length long instead of., ias described, 'onelhalf 'wave length long.. 'That is, :in general, 't'he invention is an end-on system when thesp'acin'g of the internal and external vfeeders :is ran odd multiple of :ahalf wave, land fa broadside .system when the `'radiators are `sp'ac'ed apart even Amultiples vo'f -a half wave. 'This change `does :not :affect the length of the 'terminating leads l221| which may be in any case, so far described, an odd multiple vof ra quarter 'wave length long..

It is ilo vbe also understood that the :radiators l-B, 20 may be made a `quarter wave length long `instead of ahalf Wave length long with the voltage nodal peint on Vthe radiators aft the 'joining poi-nt with the internal feeders. In this event, the length of terminating leads I221) s'hould be Yzere or an even multiple roi. -a quarter wave length.

'Toconcentr-ate the lbeam -of energy -in a direction along the axis of the radiators I8, '20, the systems so far described may be extended vertically. That is, additional radiators coaxial with those 'described may be added having phase reversing devices at the voltage maximum points. The end leads 228 Vmay simply be 'U -shaped loops, whose legs are veither zero or an even multiple of quarter wavelengths long when the radiators are an yodd multiple of a quarter wave length long. When the length loi? the 'radiators I8, 2D is an even multiple of a quarterV wave length, then .the legs of the end leads 220 should be o'dd multiples of a rquarter 'wave length long..

I claimt- 1. An end-on antenna comprising internal and external parallel-feeder members excited in phase opposition and each being one-,half wave length long, radiators serially connected thereto, the internal feeders .being adjacent whereby radiation therefrom is minimized and ,means paralleling each external feeder for neutralizing radiation therefrom, each of said neutralizing means comprising radiationless phase changers and an element similar and adiacent to the feeder connected between the phase changers.

2. .Ahrend-von antenna comprising internal and external parallel feeder members excited in phase opposition and each being one-half Ywave length long, radiators serially connected thereto, the in ternal feeders being adjacent whereby radiation therefrom is 'minimized and means paralleling each external feeder for neutralizing radiation therefrom, each of said means comprising phase changers arranged normally to the external feeders and an element similar and adjacent to the feeder connected between the phase changers,

said phase changers comprising parallel loopedY Wires one-quarter wave length long.

3. An antenna comprising pairs of linear oscillators `and linear feeders one-half wave length long serially connected and arranged -in square cpposltely and symmetrically disposed with re- Y spect `v to a 'single centerline, pairs of Ioscillators arranged transversiyto the desired direction vof Wave action serially connected to the feeders and means for neutralizing radiation `from all "or said feeders.

Vt. An antenna vcomprising A'serially connected Vradiators and feeders, v"each radiator and feeder being vsubstantial-ly inne-half 2wave length long `said feeders being arranged 'about 'a common centra! vaxis and means for neutralizing radiation from all of said feeders.

"7. An antenma. comprising half wave length radiators arranged l'transversely to a desired direction of radiant action, feeders connected to the extremities of the 'radiators in square wave fashion and rarranged. `about a common central axis, vand means for 'neutralizing radiation from all oi -said feeders.

8. An antenna comprising parallel internal 4and external feeders, radiators arranged serially between the "feeders, the internal 'feeders being spaced 'adjacent each other whereby radiation `therefrom is minimized and means paralleling ythe Vexternal feeders for neutralizing radiation Vtherefrom.

9. An antenna `comprising parallel internal and external feeders, radiators arranged serially between the feeders, the internal .feeders being spaced adjacent each other whereby 4radiation .therefrom .is minimized and means comprising `a looped wire paralleling the `external feeders for neutralizing radiation therefrom.

10. An antenna comprising :parallel internal and external feeders, feach one-half 'Wave length long, radiators one-half wave length long serially connected between said feeders, the internal 'feeders being spaced adjacent eachother whereby radiation therefrom is minimized, and means comprising a looped wire paralleling 'the external feeders for `neutralizing radiation therefrom.

11. An antenna in accordance with claim 1 characterized in this, that said radiators are onehalf 'wave length long.

12. An antenna comprising parallel pairs of internal and external feeders, all of said feeders being symmetrical with respect to a single center line separating the individual feeders of each pair, radiators arranged serially between Ythe feeders on each `side of the center line, said internal feeders `of each pair being adjacent each other on opposite sides of said center line whereby radianon therefrom is minimized. both said internal 75 and external feeders being an even multiple of half the length of the operating Wave. I

13. An antenna comprising pairs of parallel oscillators, feeders serially connecting together al1 of said pairs, all of said feeders being parallel to each other, and means for neutralizing radiation from all of said parallel feeders.

14. An antenna comprising pairs of coaxial linear radiators arranged in the same plane symmetrical with respect to a center line, feeder Wires for serially connecting together at their corresponding ends the adjacent radiators of said pairs on each side of said center line so as to constitute the Whole on each side of said center line, a single series circuit of general zigzag form, and means for neutralizing radiation from said feeder wires.

15. An antenna comprising pairs of coaxial linear radiators arranged in the same plane symmetrical with respect to a center line, internal and external feeder wires for serially connecting together at their corresponding ends the Aadjacent radiators of said pairs on each side of said center line so as to constitute the Whole on each side of said center line, a single series circuit of general zigzag form, and means for neutralizing radiation from said external feeder Wires.

NILS E. LINDENBLAD. 

